A generic camshaft adjusting device of the pre-cited type is known from EP 0 799 976 A1 and comprises a drive pinion configured as an outer rotor which is connected in driving relationship to a crankshaft of an internal combustion engine by a traction means, and a winged wheel configured as an inner rotor and connected rotationally fast to a camshaft of the internal combustion engine. The drive pinion comprises a hollow space defined by a circumferential wall and two side walls, into which hollow space is inserted the winged wheel which comprises four radially arranged wings on the periphery of its wheel hub. Four hydraulic working chambers are defined within the hollow space of the drive pinion by four uniformly spaced limiting walls which extend from the inner surface of the circumferential wall toward the central longitudinal axis of the drive pinion. Each of the working chambers is divided into two hydraulic pressure chambers by one of the wings of the winged wheel. The radial end faces of the limiting walls of the drive pinion are in sealed contact with the wheel hub of the winged wheel by sealing strips arranged in axial retaining grooves, while, at the same time, the radial end faces of the wings of the winged wheel are in sealed contact with the inner surface of the circumferential wall of the drive pinion by sealing strips likewise arranged in axial retaining grooves. Thus, by an optional successive or simultaneous pressurizing of the pressure chambers by a hydraulic pressure medium, the winged wheel can be turned and/or fixed relative to the drive pinion to obtain a relative rotation and/or a continuous hydraulic clamping of the camshaft relative to the crankshaft.
A drawback of this prior art device is that, besides the radial sealing of the individual pressure chambers from one another by the sealing strips on the radial end faces of the wings and the limiting walls, no measures are provided for an axial sealing of the pressure chambers of the device from one another. Thus, particularly when manufacturing tolerances in the axial dimension of the drive pinion and the winged wheel add up and produce a relatively large axial play between the winged wheel and the drive pinion, it is possible that internal pressure medium leaks or hydraulic short circuits between the pressure chambers, which always have a detrimental effect on the functioning of the adjusting device, take place through the gaps formed between the wings of the winged wheel and the side walls of the drive pinion. These malfunctions manifest themselves generally in the form of reduced adjusting speeds of the device which are the cause of a delayed response of the device to changing conditions of operation of the internal combustion engine, or in the form of an insufficient hydraulic clamping of the winged wheel in the drive pinion, so that the desired angular position of the camshaft relative to the crankshaft cannot be exactly maintained.
Further, DE-OS 39 22 962 discloses the use of axial sealing strips arranged in radial retaining grooves on the end surfaces of the wings in addition to the radial seals on the end faces of the wings in a camshaft adjusting device likewise comprising a drive pinion with four working chambers and a winged wheel with four wings.
However, such a sealing of the individual pressure chambers of the device has the drawback that it requires a large number of separate sealing strips and thus considerably more assembly work is involved in the manufacturing of the device. Moreover, due to the joint gaps naturally formed between the individual sealing strips, high pressure medium leakage can still occur so that the aforesaid resulting malfunctions of the device are not completely eliminated by such a sealing arrangement.